Process of imparting oil-repellency to solid materials



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This invention relates to novel processes for rendering solid materials oil-repellent and to the novel materials thus produced. By solid materials herinabove I mean water-insoluble materials customarily employed in the manufacture of articles of utility, for instance textile fabric, textile yarns, leather, paper, plastic sheeting, wood, ceramic clays, as well as manufactured articles prepared therefrom such as articles of apparel, wall paper, paper bags, cardboard boxes, porous earthenware, etc. By oil repellency, for the purpose of definiteness, I shall refer hereinafter to the quality of repelling, under the standard tests herein discussed, a light mineral oil such as a commercial liquid hydrocarbon or a vegetable oil such as peanut oil. But as a general proposition the materials treated according to this invention are found to possess repellency to oils, greases and fats generally, regardless of their origin (as for instance, mineral, vegetable or animal kingdom) or their consistency.

It is a primary object of this invention to provide a novel means of imparting oil-repellency to water-insoluble solid materials which is applicable to said material from an aqueous treating bath. Another object is to provide a novel means as aforesaid which is applicable from aqueous baths by ordinary means such as padding, dipping, impregnation, spraying, etc. Other objects and achievements of this invention will become apparent as the description proceeds.

Oil-repellency in articles such as wearing apparel, cardboard boxes, paper bags or wrapping paper is a relatively young and not fully developed art. The demand for such articles is perhaps old enough. The advantages of having for instance grease-repellent overalls for mechanics, wallpaper that does not stain easily, oil-repellent paper bags for bakery goods, oron the contrary-containers which will keep the contents safe against contamination with greasy soil from the outside, are so obvious as not to require much elaboration. Hitherto, however, the solution to this problem has not been entirely satisfactory from the economical viewpoint. Some of the oil-repellency agents hitherto used or suggested are complicated and costly chemicals. Others can be applied only from an organic solvent. Still others are relatively inefiicient and require application of large quantities thereof with respect to the weight of the fiber or solid material being treated therewith.

I have now found that highly effective oil-repellency efiects can be produced on solid materials such as above indicated by applying to the same an aqueous solution of a polyfluoroalkyl phosphate of the group defined by the formulas wherein m is an integer from 3 to 12, n is an integer from 6 to 12, y is a number of average value from 1.0 to 2.5, and Z is a member of the group consisting of hydrogen atent O 3,096,207 Patented July 2, 1963 and water-solubilizing cationic ions. The treated material is then dried, whereby to form in intimate contact therewith an evenly distributed deposit of said polyfluoroalkyl phosphate.

As examples of water-solubilizing cations in the definition of Z above, may be mentioned the alkali-metals (Na, K, Li), ammonium, diethanolammonium, triethanolammonium, morpholinium, and the like.

Compounds falling within the above general formulas are disclosed in U.S.P. 2,597,702 and 2,559,749, which assign to them the special property of being excellent dispersing agents. In the second of said two patents, the said compounds have been suggested for use as dispersing agents in the polymerization of unsaturated organic compounds. But their quality as oil-repellency agents has, to the best of my knowledge, not been recognized heretofore.

I now find, however, that the above defined polyfluoroalkyl phosphates not only possess the desirable quality of imparting oil-repellency to solid bodies, but some of them are highly potent in this respect. This is particularly true of compounds of the above formulas wherein y is 2. And inasmuch as the synthesis of these phosphates naturally results in a mixture of phosphates of diiferent degrees of esterification, I find that for the purposes of this invention, mixtures of bisand mono-polyfluoroalkyl phosphates in which the bis compounds predominate constitute the most desirable agents for practical use. Expressed in difierent words, they are mixtures of compounds falling within one or the other of the above formulas and wherein y has an average value from 1.0 to 2.5 with a preferred range of Furthermore, the mixtures can be practically separated, and where the intended use justifies the added cost of separation, the compounds wherein y equals 2 constitute the preferred agents.

The above compounds possess also other valuable prop erties for the purpose intended. For instance, their water-solubility adapts them for application from a purely aqueous bath or, if desired, from an aqueous bath containing acetone, alcohol, or any other water-miscible, volatile adjuvant.

The compounds defined have also the quality of versatility, being applicable to a wide variety of textile fibers, including cotton, viscose, cellulose acetate, Wool, silk, nylon, acrylic fiber and polyester fiber. They are also applicable to leather, paper, wood and unglazed earthenware.

I As practical illustrations of compounds falling within the above Formulas I and II and useful for the purposes of this invention, the alkalimeta1, ammonium, etc., salts or the free acid form of the following phosphoric acids come into consideration.

H(OFr)aCHzO P (OH):

mormomohr H(CF2)5CH2O P (OHM [H(CF2) sCHzO]2P\ H(OF2)10CH2OP (OH)? The nomenclature of these compounds is rather complicated, but is typified by the following samples:

'Item 2: bis(1H,1H,7H-dodecafluoroheptyl) phosphate Item 9: 1H,lH-tridecafluoroheptyl phosphate Item 12: 'bis(1H,lH-pentacosafluorotridecyl) phosphate Many of the above compounds are named in U.S.P.

2,559,749 and 2,597,702, and those not named may be' TESTING OF SURFACE-TREATED, SHEET MATERIAL This test is based on the different penetrating properties 'of mineral oil (Nujol) and n-heptane. Mixtures of these two hydrocarbon liquids, which are miscible in all ,proportion, show penetrating properties proportional to. the amount of n-heptane in the mixture.

'To measure oil repellency of a treated fabric 8" x 8" swatches of the fabric are placed on a table and a drop of one of severaltest-mixtures of the above hydrocarbonsis gently placed onto each fabric surface. After 1 minute, the fabrics are inspected to determine the mixture of highest heptane percentage which did not wet the fabric under the drop. According to said highest heptane percentage, the fabric is assigned a rating as set forth in the following table: 7

7 Percent by Percent by Oil-Repellency Rating Volume Volume Heptane Nuiol O (N o resistance to Nujol; i.e. penetration within 3 minutes).

Usually, acceptable ratings are 70 and above, although beneficial effect to oil staining is sometimes obtained with ratings as low as 50.

Example 1 100 parts of cotton fabric are dipped into an aqueous bath containing 1000 or more parts of water and 1 part by Weight (i.e. 1%'O.W.F.) of ammonium bis(lH,lH,9H- hexadecafluorononyl) phosphate. After agitating in said bath for 5 minutes or more, the fabric is removed, squeezed and air-dried.

The above procedure is applicable likewise to other fabrics, such as wool, nylon, polyester fabric, acrylic fabric, to the corresponding mater-ials in the form of yarn, as well as to leather.

Ina series of actual experiments according to the above procedure followed by the oil-repellency test hereinabove described, oil-repellency ratings of 50 were obtained on all fabrics above mentioned. When, however, the same set of experiments is repeated except for increasing the concentration of the polyfluoroalkyl phosphate to 2% O.W.F., ratings as high as 80 are obtained.

Example 2 Following the procedure of Example 1, cotton muslin Was impregnated with an aqueous bath containing a quantity of ammonium 1H,lH,llH-eicosafluoroundecyl phosphate corresponding in weight to 4% of the weight of the fabric. Upon drying, the fabric was found to have an oil rating of 70 by the standard test above described.

When the above experiments were repeated with wool flannel and with unsized paper, analogously high oil-repellency ratings were obtained in each case.

Example 3 Unsized paper was treated according to the procedure set forth in Example 1, but using as oil-repellency agent an essentially 50:50 mixture (by weight) of monoand 'bis-polyfluoroalkyl phosphates obtained by reacting with phosphorus pentoxide in toluene (according to second part of Example IV of Banning, U.S.P. 2,597,702) upon a mixture of polyfluoroalcohols comprising 50 mole percent 1H,lH,5H-octafluoro-l-pentanol, 33% 'lH,1H,7H-

dodecafluoro-l-heptanol, and 17% lH,1H,9H-hexadeca-V solution of any other convenient concentration. In some, cases, preparation of the aqueous solution of the polyfluoroalkyl phosphates may be facilitated by first dissolving the agent in an organic solvent, such as acetone,

methanol, or ethanol, followed by dilution with water, or a a solution of the free acid phosphate in an organic solvent as aforenoted may be diluted With an aqueous amine or ammonia solution.

The quantity of the phosphate agent added may vary from 0.05 to 10% O.W.F. The optimum amount will depend upon such factors as the nature of the material being treated, the composition of the phosphate, and the degree of oil-repellency desired.

The ammonium salts or amine-addition products of the phosphates are more elfective than the free phosphoric acid, and the wF-compounds (Formula -I) are more potent than the UH-compounds (Formula II). Moreover, with either kind, the bis-fluoroa-lkyl phosphates are immensely more eflective than the mono compounds, and where mixtures are unavoidable, it is preferred to use such mixtures wherein the bis-fiuoroalkyl compounds predominate (i.e. vy has an average value greater than 1.5).

- Fully alkylated phosphates (i.e. 3 :3) are inoperable,

but where a mixture is readily available, they constitute an inert, but harmless diluent to the active bis-compounds.

Therefore, mixtures of polyfiuoroalkyl phosphates having a y-value greater than 2, say up to y=2.5, are tolerable. Altogether then, compounds wherein y=2 are preferred, but mixtures having an average y-value between 1.0 and 2.5 can be used.

The wF-cornpounds (Formula I) may be generically referred to as (perfluoroalkyl-methyl) phosphates. It follows from the aforegoing discussion that the most p tent compounds for the purposes of this invention, and therefore the most desirable from the pr-atioal viewpoint, are the bis(perfluoroalkyl-methyl)ammonium phosphates.

Incidentally, the wF-compounds possess the added advantage that they also impart water-repellence to the treated articles. Thus, while production of oil-repellent solid articles has been stressed throughout the above discussion as being the primary object of this invention, the process and means herein described, when wF polyfiuoroalkyl phosphates are employed, produce both oil-repe lence and water-repellence on the article treated therewith, be it textile fiber, paper or any other water-insoluble, solid material.

I claim as my invention:

1. The process of rendering a water-insoluble solid material oil repellent which comprises treating said material with an aqueous bath containing a water-soluble polyfluoroalkyl phosphate of the group defined by the formulas and wherein m is an integer from 3 to 12, n is an integer from 6 to 12, y is a number of average value from 1.0 to 2.5, and Z is a member of the group consisting of hydrogen and water-solubilizing cationic ions, and drying the material whereby to form in intimate contact therewith an evenly distributed deposit of said polyfiuoroalkyl phosphate.

2. A process as in claim -1, wherein the polyfiuoroalkyl phosphate selected is a mixed product in which the dominant component is a compound whose y-value is 2.

3. A process as in claim 1, wherein the phosphate selected is a bis-polyfluoroalkyl phosphate.

4. A process as in claim 1, wherein the phosphate selected is a bis(perfiuoroalkyl-methyl)ammonium phosphate.

5. A process as in claim 1, wherein the phosphate selected is ammonium bis(1H,lH-pentadecafluorooctyl) phosphate.

6. A process as in claim 1, wherein the phosphate is ammonium bis(1H,lH,9H-hexadeoafluoro=nonyl) phosphate.

7. A process as in claim 1, wherein the amount of said polyfluoroalkyl phosphate deposited on said material is from 0.05 to 3.0% by weight thereof.

8. A process as in claim 1, wherein the material being treated is a member of the group consisting of textile fibers and fabrics, leather, paper sheeting and synthetic plastic sheet material.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE PROCESS OF RENDERING A WATER-INSOLUBLE SOLID MATERIAL OIL REPELLENT WHICH COMPRISES TREATING SAID MATERIAL WITH AN AQUEOUS BATH CONTAINING A WATER-SOLUBLE POLYFLUROALKYL PHOSPHATE OF THE GROUP DEFINED BY THE FORMULAS
 8. A PROCESS AS IN CLAIM 1, WHEREIN THE MATERIAL BEING TREATED IS A MEMBER OF THE GROUP CONSISTING OF TEXTILE FIBERS AND FABRICS, LEATHER, PAPER SHEETING AND SYNTHETIC PLASTIC SHEET MATERIAL. 